Interferon was first found in cytokines which are produced in the virus-infected cells and is known as the cytokine with the most remarkable antiviral activity.
Although interferon was first found as a compound with inhibitory effect against influenza virus or other viruses while being produced from the influenza virus-infected chick embryonic cells, there have been many attempts to use interferon for treating other types of diseases after its discovery. As a result, it has been found that interferon can be used for the treatment of various viral diseases, chronic hepatitis B and C, hematologic malignancy, and multiple sclerosis. The effects and stability of interferon were confirmed especially in the patients with Immunocompetence. In addition, it was recently found that interferon has inhibitory effect against HIV infection. Therefore, increasing the expression of interferon can enhance the immunity.
In general, virus can infect various hosts including humans, animals, plants, and microorganisms (Patton J T, Caister Academic Press, 2008). Among those virus, rotavirus which is a type of dsRNA virus belongs to Reoviridae family and it is one of the main causes of severe diarrhea worldwide in young animals (including cow, pig, dog, and goat) and infants. In addition to severe diarrhea, rotavirus may also cause encephalitis, otitis media, necrotizing colitis, hepatapostema, and intussusception (Ester, M. K. Fields Virology, 2001, 1747-1785). In order to treat the rotavirus-associated diseases, methods for direct targeting of virus have been developed such as reducing the absorption of virus to epithelial cells, reducing the invasion of cell by virus, inhibiting transcription and replication of viral genes and protein synthesis, and inhibiting virus release from cell. Until now, numerous vaccines targeting rotavirus have been developed. Also, animal-human recombinant virus vaccine is prepared and manufactured for human treatment by recombining rotavirus from human and animal. The representative animal-human recombinant virus vaccine is a vaccine prepared by inserting the gene encoding for human rotavirus serotype VP4 into a cow rotavirus WC3 as a template, and the vaccine from RotaTeq—Merck was approved by FDA in 2006 and has been sold. However the recombinant virus vaccine may cause side effects such as intrussusception, and thus it involves a huge disadvantage in that it cannot be used for preventing other rotavirus serotypes. To overcome the disadvantage of vaccine, there have been studies on natural products that can suppress rotavirus. As an example, Takahashi et al. have reported that hot water extracts of Stevia have anti-rotavirus effects (Takahashi, K et al., Antiviral Res. 2001, 49, 15-24). However, when the natural products or vaccines are used for direct targeting of virus, this may cause virus to acquire resistance to antiviral agents and also other mutations at a high frequency. Therefore, in order to resolve this problem, a lot of studies have focused on developing a method for accompanying the suppression of the excessive inflammatory response of host which is induced by infection, rather than killing the virus itself, so that a severe inflammatory disease by viral infection can be prevented (Geller J. et al, Biochemical Pharmacology, 2010, 413-420).
For a number of years, the genetic engineering or bioengineering approaches have been used to produce a large scale of interferons for developing an antiviral agent and immune enhancing agent. Recently, there have been many studies on investigating the natural products or synthetic chemicals to identify the compound that can induce an interferon activity. However, the compound that shows a high inductive effect of interferon in humans has not been identified yet (Alcaro S et al., Bioorg Med Chem. 2005, 13(10), 3371-3378). Although 3M Pharmaceuticals has developed a strong interferon inducer called lmiquimod(1), there have been multiple side effects identified from its clinical tests, stopping the inducer from being commercialized.